JP6869765B2 - Plasma processing equipment and plasma processing method - Google Patents

Description

The present invention relates to a plasma processing apparatus and a plasma processing method in which a substrate-like sample such as a semiconductor wafer arranged in a processing chamber inside a vacuum vessel is processed by plasma formed in the processing chamber, and a plurality of types having different compositions. The present invention relates to a plasma processing apparatus and a plasma processing method for processing a sample using the plasma formed by switching the processing gas of the above and supplying it into the processing chamber.

Due to the miniaturization of semiconductor devices in recent years, the etching accuracy is shifting from the nm order to the Å order. Controlling the etching process on the order of Å is an important issue.

Generally, in order to improve the controllability of etching in the etching process, it is necessary to improve the controllability by shortening the step time that contributes to etching during continuous discharge. Reproducibility and machine differences have been problems as issues during the original continuous discharge.

In the conventional plasma processing apparatus, in order to suppress the reproducibility and the machine difference which are the problems at the time of continuous discharge, the inert gas is affected by the influence of different etching gases being mixed at the time of step transition in the continuation of discharge between different steps. It was suppressed by using the transition step using. As such a prior art, those described in Japanese Patent Application Laid-Open No. 2007-287924 (Patent Document 1) have been known.

In the present prior art, a sample arranged in the processing chamber is processed by using a plurality of processing steps performed by forming plasma in the vacuum processing chamber, and the pressure, the type of processing gas, and the like are conditions for each. Disclosed is a technique for arranging a transition step of supplying an inert gas, eg Ar gas, capable of continuing to discharge the plasma between different processing steps. Further, in the present prior art, in the transition step, there is disclosed that the pressure in the vacuum processing chamber is initially adjusted to that of the previous processing step and then smoothly changed to the pressure of the subsequent processing step. As described in Japanese Patent Application Laid-Open No. 2008-91651 (Patent Document 2), a gas line connected to a gas line for supplying a processing gas supplied to the processing chamber, branched, and exhausted to an exhaust pump for the processing chamber. It has been known that the flow of the processing gas to these gas lines is switched by the operation of the valve to adjust the supply of the processing gas to the processing chamber.

JP-A-2007-287924 Japanese Unexamined Patent Publication No. 2008-91651

The above-mentioned prior art has a problem because the following points are not sufficiently considered.

That is, in Patent Document 1, at the start of the transition step using the inert gas, one mass flow controller adjusts the flow rate of the inert gas so as to match the pressure in the previous processing step, and then the mass flow controller adjusts the flow rate. We made changes to match the pressure conditions of the next step. At that time, since the flow rate is changed by one mass flow controller, it takes time to change the flow rate and to establish the pressure inside the pipe after that, so shortening the transition step has been an issue.

Further, even in the actual process step, when a mass flow controller having the same flow rate and the same gas type is used for changing the flow rate, there is a problem that the switching time is controlled by the flow rate change time. In addition, in order to switch, it was necessary to prepare two mass flow controllers with the same flow rate and the same gas type, and it was an issue to increase the production cost and secure the mounting space for the mass flow controller.

In addition, the conventional technology has a gas line for introducing a processing chamber and a gas line for exhausting the gas line to a dry pump with good reproducibility of gas flow rate and gas pressure at high speed and smoothly, and the processing gas is switched by a valve. In the gas supply unit, when multiple gas types are used for switching, the gas is processed from the state where the gas is mixed once in the gas line for exhausting to the dry pump. When switching to the gas line for room introduction, the gas is mixed again, so there is a problem that pressure fluctuation occurs at that time and it takes time to establish it.

In addition, in order to suppress the responsiveness variation 0.1s when opening and closing the valve, there is a method of first closing the gas line valve on the exhaust side with the dry pump, but the opening and closing speed of the valve is the opening and closing speed of the solenoid valve and the air tube that connects the valve. It depends on the length and thickness, and it is long under the actual device mounting conditions, and in some cases it takes nearly 0.2 s. In addition, the conventional technology does not consider the communication time of the valve opening / closing time device system, and the communication time is long. There was an instruction delay variation of about 0.1 s to 0.2 s. Therefore, considering the margin for that amount, the valve must be closed 0.5 s or more before, and the pressure fluctuation caused by the pressure rise in the integrated block at that time has been a problem.

Further, when the valve is closed 0.5 s or more before, about 1 s is required for the rise time of the mass flow controller of the gas to be flowed next and the pressure establishment time of the gas line in advance. Therefore, it is necessary to start flowing the gas 2.5 s or more before the switching, which has been a problem for realizing a short-time switching of 2 s or less.

Further, in order to solve the problem of valve opening / closing time, if a valve for high-speed switching of a type in which the solenoid valve is directly mounted on the valve is used, switching can be performed in about 15 ms, but the solenoid valve is mounted directly on the valve. In addition to increasing the space occupied in the gas supply unit, the cost increase per valve has been an issue.

Further, in the prior art, it is necessary to shorten the pipe length in order to improve the responsiveness until the flow rate in the pipe of the gas line for introducing the processing chamber from the gas supply unit to the chamber becomes a steady state. This was done by bringing the gas supply unit body closer to the chamber, but there are large space restrictions to bring the gas supply unit body, which has a relatively large volume, closer to the chamber, and the pipe length is about 1 m for mounting. There was a problem that it was necessary.

Further, as a conventional technique, when performing high-speed control of a processing gas, there has been a problem of reproducibility and machine error of control parameters other than the processing gas flow rate controlled at high speed by gas switching and the associated chamber pressure. Such control parameters include microwave power matching for plasma generation, coil current, and wafer bias matching. In addition, there is a transient response time for each control parameter within the step time, and since that part cannot be controlled, it causes deterioration in reproducibility and a factor that causes a difference.

In the prior art, the matching time of microwave power is considered to be 0.2 s at maximum, the stabilization time of coil current is 2 s at maximum, and the matching of wafer bias is 0.5 s at maximum. On the other hand, if the step time is shortened by high-speed control of the processing gas, the ratio of the transient response time to the whole increases. It is difficult to adjust the influence of the processing in this transient response time on the processing result, and as a result, there is a problem that the processing yield is lowered. Further, there is a problem that the reproducibility of processing during such a transient response period is low and the difference (machine difference) between devices becomes large. Such a problem has not been taken into consideration in the above-mentioned prior art.

An object of the present invention is to provide a plasma processing apparatus or plasma processing method with improved processing yield.

The above purpose is to supply a predetermined flow rate of processing gas to a processing chamber arranged inside a vacuum vessel through a gas supply unit, and to provide wafers placed on a sample table arranged in the processing chamber under different conditions. A plasma treatment apparatus or method for processing in a step including a plurality of treatment steps for forming plasma in a treatment chamber using the treatment gas supplied in the above step, wherein the step is between the two treatment steps before and after the treatment. In the transition step in which the rare gas is supplied into the treatment chamber, the rare gas is supplied after adjusting its pressure so as to be equal to the conditions of the treatment gas used in the previous treatment step. After the first transition step and the first transition step, the rare gas is supplied with its pressure and flow rate adjusted to be equal to the conditions of the processing gas used in the subsequent processing step. The gas supply unit includes a transition step including a second transition step, and the gas supply unit is used for the gas introduction line connected to the vacuum vessel and the processing steps used in the plurality of processing steps communicated with the gas introduction line. A first gas supply line for supplying gas, a second and third gas supply lines for which the rare gas used in each of the first and second transition steps is supplied, and a first, second, and second gas supply line. The first and second waste gas lines connected to each of the three gas supply lines and communicated with the exhaust pump, the first, second and third gas supply lines, the gas introduction line and the first and first It comprises at least one valve that opens and closes communication with each of the second waste gas lines, the valve depending on the two processing steps of the step and the first and second transition steps between them. This is achieved by switching and processing the wafer.

According to the present invention, it is possible to reduce the deterioration of reproducibility of process performance and the machine error, which are problems in the short-time step, and it is possible to realize the short-time step.

It is a vertical cross-sectional view schematically showing the outline of the structure of the plasma processing apparatus which concerns on embodiment of this invention. It is a block diagram schematically showing the outline of the structure of the matching circuit provided in the Example shown in FIG. 1. It is a table which showed a part of the condition in each of the plurality of steps of the etching process carried out by the Example shown in FIG. It is a graph which shows the flow of operation of the process shown in FIG. It is a figure which shows typically the gas flow in the processing step A carried out by the plasma processing apparatus which concerns on Example of FIG. It is a figure which shows typically the gas flow in the transition step 1 carried out by the plasma processing apparatus which concerns on Example of FIG. It is a figure which shows typically the gas flow in the transition step 2 carried out by the plasma processing apparatus which concerns on Example of FIG. It is a figure which shows typically the gas flow in the processing step B carried out by the plasma processing apparatus which concerns on Example of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In the following examples, a processing chamber to which a vacuum exhaust device is connected and sealed by a dielectric window capable of depressurizing the inside and a vacuum container, a substrate electrode on which a material to be processed can be placed, and a substrate electrode facing the substrate electrode. A provided shower plate, a gas supply unit for supplying a processing gas into the processing chamber, a high-frequency introduction means for introducing an electromagnetic wave for generating a plasma from the dielectric window, and a high-frequency introducing means for generating the plasma. In a plasma processing apparatus having a means for forming a magnetic field, a gas switching mechanism is provided separately from the gas supply unit on a first gas supply line that supplies processing gas from the gas supply unit to the decompression processing chamber via a shower plate. A plasma processing apparatus equipped with the above and a processing process by the same are shown.

The gas switching mechanism of this embodiment includes two waste gas lines connected to two connecting gas introduction lines and a rough exhaust line, nine valves for switching them, a chamber introduction line, and a pressure gauge for measuring pressure. It is constructed by two pressure gauges for measuring the pressure of the two waste gas lines and two pressure controllers that control the pressure of the chamber introduction line and the waste gas line in the same manner. Using this mechanism, the pressure of the waste gas line should be the same as the pressure of the chamber introduction gas line while pre-flowing the gas to the waste gas line and keeping it in a steady flow before each condition starts. By adjusting, it is possible to connect smoothly without fluctuation.

Further, by providing the gas switching mechanism separately from the inside of the gas supply unit, it is possible to use a valve for high-speed switching in which the solenoid valve is mounted on the valve without being confined to the space in the gas supply unit. Further, by using the valve for high-speed switching, it is not necessary to shift the switching timing of opening and closing in consideration of the response delay of the valve, and the switching step can be shortened.

In addition, since gas switching can always be performed using a transition step using an inert gas and an additional mass flow controller for the transition step at the time of high-speed switching, even when the same gas type and the same gas flow rate are used in the processing step, It is not necessary to respond by changing the flow rate, and the processing step can be shortened, or the product cost can be kept low because it is not necessary to equip the gas supply unit with two mass flow controllers of the same gas type and the same flow rate. ..

In addition, since the operation inside the gas supply unit is the same as before, it is not necessary to replace the valve in the gas supply unit with an expensive valve for high-speed switching, and only the gas switching mechanism needs to use the valve for high-speed switching. Therefore, the product cost can be kept low.

Further, by arranging the gas switching unit on the downstream side of the gas supply unit, even when a plurality of gas types are used, the gas is switched after the steady flow is performed in the state where the plurality of gases are mixed. Unlike the technology, it is not necessary to mix the gas again when switching the gas, and the pressure fluctuation generated in the processing gas pipe at that time can be suppressed.

As an operation of the actual processing step, a transition step is used between the processing step A and the processing step B. This transition step is divided into the first half and the second half, and in the first half transition step 1, the microwave power, coil current, and processing chamber pressure of the pretreatment step condition A are maintained, the wafer bias power is turned off, and the gas flow rate is set. Switch to argon or an inert gas equivalent to the same flow rate. Next, in the latter half of the transition step 2, while maintaining the wafer bias power OFF, it is switched to the microwave power, coil charge, and processing pressure condition of the next processing step condition B, and is equivalent to the same gas flow rate in the processing step condition B. Switch to Ar or inert gas. By switching between microwave power, coil current, processing chamber pressure, and gas flow rate within the transition step, the matching time of microwave power, the establishment time of coil current, and the effect of these transient response times on reproducibility and machine error Can be reduced. Further, the matching value of the wafer bias matching circuit is adjusted in advance to the matching value of the next processing step when it is in the OFF state, thereby suppressing the transient response.

It is possible to reduce the deterioration of reproducibility of process performance and the machine difference, which are problems of the prior art, and to realize a short step.

Hereinafter, examples of the present invention will be described with reference to FIG. FIG. 1 is a diagram showing a plasma processing apparatus according to an embodiment of the present invention. In particular, in this embodiment, it is a plasma processing apparatus that performs microwave ECR (Electron Cyclotron Resonance) etching.

FIG. 1 is a vertical cross-sectional view showing an outline of the configuration of the plasma processing apparatus according to the embodiment of the present invention. In this figure, in the plasma processing apparatus according to the embodiment of the present invention, a sample table 10 on which a wafer 11 which is a sample to be processed in a substrate shape is placed and held is arranged, plasma is formed, and the wafer 11 is processed. A vacuum vessel 1 having a processing chamber 4 inside, an exhaust device unit having a turbo molecular pump 20 arranged below the vacuum vessel 4 to exhaust the inside of the processing chamber 4, and an upper portion of the processing chamber 4 outside the vacuum vessel 1 and its like. A semiconductor manufacturing apparatus that includes a plasma forming portion that is arranged around the periphery and generates an electric field or a magnetic field for plasma formation that is supplied into the processing chamber 4 and performs a step of etching a wafer 11 to manufacture a semiconductor device. Is.

The vacuum vessel 1 of the plasma processing apparatus of this embodiment is a cylindrical side wall having a cylindrical shape or an approximate shape that can be regarded as the same, and a lid member arranged above the cylindrical side wall so as to be openable and closable. It is provided with a dielectric window 3 (for example, made of quartz) having a plate shape and made of a dielectric material capable of transmitting an electric field or a magnetic field. The dielectric window 3 and the upper end of the side wall are connected by sandwiching a sealing member such as an O-ring between them, and the inside and outside of the processing chamber 4 inside the vacuum vessel 1 are airtight with the dielectric window 3 connected. It is sealed and held, and the vacuum vessel 1 is configured with the dielectric window 3 as a member constituting the upper portion thereof.

Below the dielectric window 3, a ceiling surface of the processing chamber 4 inside the vacuum vessel 1 is formed, and a plurality of through holes for supplying processing gas from above are arranged in the processing chamber 4. A shower plate 2 which is a plate member made of a dielectric having a disk shape (for example, made of a material containing ceramics such as quartz or yttria) is arranged. Between the shower plate 2 and the dielectric window 3, a buffer space is arranged in which the processing gas supplied into the processing chamber 4 from the through hole is supplied, diffused, dispersed and filled.

The inside of the space for the buffer is connected to the gas supply device 16 that supplies the processing gas to the plasma processing device, and the gas for etching processing supplied from the gas supply device 16 is connected to the vacuum vessel 1 for gas supply. It passes through the inside through the etching gas line 22 including the tube. Further, a gas switching unit 100 is provided between the etching gas line 22 for supplying the processing gas from the gas supply unit 16 to the decompression processing chamber via the shower plate 2 and the chamber introduction gas line 25. A variable conduction valve 18, a turbo molecular pump 20, and a dry pump 19 are arranged below the vacuum vessel 1 and communicate with the processing chamber 4 via a vacuum exhaust port 5 arranged on the bottom surface of the processing chamber 4 in the vacuum vessel 1. ing.

In order to transmit the electric power for generating plasma to the processing chamber 4, a waveguide 6 (or an antenna) is arranged above the dielectric window 3 as a high-frequency introduction means for radiating electromagnetic waves.

The direction of the waveguide 6 is changed by connecting the cylindrical tubular portion of the waveguide 6 extending in the vertical direction to one end of the tubular portion having a rectangular cross section extending in the horizontal direction at the upper end. Further, on the other end side of the tubular portion having a rectangular cross section, an electromagnetic wave generation power supply 8 for oscillating and forming an electromagnetic wave transmitted into the waveguide 6 is arranged. The frequency of this electromagnetic wave is not particularly limited, but in this embodiment, a 2.45 GHz microwave is used.

A magnetic field generating coil 9 that forms a magnetic field is arranged on the outer peripheral portion of the processing chamber 4 above the dielectric window 3 and on the outer peripheral side of the side wall of the cylindrical portion of the vacuum vessel 1, and oscillates from the electromagnetic wave generating power source 8. The electric field introduced into the processing chamber 4 via the waveguide 6, the cavity resonator 7, the dielectric window 3, and the shower plate 2 is supplied with a DC current and formed by the magnetic field generating coil 9, and is formed in the processing chamber. By interacting with the magnetic field introduced into 4, the particles of the etching gas are excited to generate plasma in the space below the shower plate 2 in the processing chamber 4. Further, in this embodiment, a sample table 10 is arranged in the lower part of the processing chamber 4 and below the shower plate 2 so as to face the lower surface thereof.

In this embodiment, the sample table 10 has a substantially cylindrical shape, and a dielectric film (not shown) formed by spraying is arranged on the upper surface thereof on which the wafer 11 to be processed is placed. A DC power source 15 is connected to at least one film-shaped electrode arranged inside the dielectric film via a high-frequency filter 14 so that DC power can be supplied. Further, a disk-shaped conductor-made base material is arranged inside the sample table 10, and the high-frequency power supply 13 is connected via the matching circuit 12.

The plasma processing device of this embodiment can transmit and receive signals to and from the vacuum vessel 1, the exhaust device, the parts constituting the plasma forming part, the gas switching unit 100, the matching circuit 12, the high frequency power supply 13, and the like. It has a connected control unit (not shown). In the plasma processing apparatus of this embodiment, in the step of etching the wafer 11 described below, the software stored in the hard disk in the control unit or the storage device such as CD-ROM, RAM or ROM is read out. Command signals calculated by the operation of an arithmetic unit such as a semiconductor microprocessor based on the algorithm described therein are transmitted to each of these parts to adjust these operations, and the wafer 11 is etched. To. The control unit is a unit in which such a storage device, an arithmetic unit, and an interface for transmission / reception are communicably connected, and may be composed of one or a plurality of devices.

In such a plasma processing apparatus, the wafer 11 in which a film structure in which a plurality of film layers including a mask layer using a resin material are laminated is previously formed on the upper surface is treated with the film layer to be processed. In the untreated state, the film layer to be processed is etched by being conveyed to the inside of the processing chamber 4, held on the upper surface of the sample table 10, and using the plasma formed in the processing chamber 4. .. More specifically, the unprocessed wafer 11 is connected to the side wall of the vacuum container 1 (not shown), and the transfer chamber of the vacuum transfer container in which the transfer means such as the robot arm is arranged inside the transfer chamber whose pressure is reduced is increased. It is conveyed and carried into the processing chamber 4 through the inside of the gate, which is a through hole arranged on the side wall of the vacuum vessel 1.

The untreated wafer 11 held on the transport means is placed on the upper ends of a plurality of pins protruding above the upper surface of the sample table 10 arranged in the sample table 10 and delivered. A wafer in which a transfer means such as a robot arm is carried out from the processing chamber 4 and a gate valve (not shown) closes the gate airtightly, and a pin is lowered inside the sample table 10 and stored and delivered to the upper surface of the sample table 10. 11 is attracted to the upper surface of the sample table 10 by the electrostatic force of the DC voltage applied from the DC power source 15.

Next, the etching gas, which is a predetermined processing gas, is supplied from the gas supply unit 16 into the processing chamber 4, and the result of detecting the pressure inside the processing chamber 4 by the pressure gauge 17 is fed back to operate the variable conductance valve 18. Is adjusted and the inside of the processing chamber 4 is adjusted to a pressure suitable for processing. In this state, an electric field and a magnetic field are supplied into the processing chamber 4, and atoms or molecules of the processing gas supplied into the space in the processing chamber 4 between the sample table 10 and the shower plate 2 are dissociated and ionized. Plasma is formed in the processing chamber 4. In the state where the plasma is formed, a high-frequency power of a predetermined frequency is applied to the sample table 10 from the high-frequency power supply 13, a bias potential is formed above the wafer 11, and the potential difference between the bias potential and the plasma potential is increased. The charged particles in the plasma are attracted to the surface of the wafer 11 and collide with the film structure on the surface of the wafer 11 to etch the film to be processed.

In the etching process of this embodiment, as the time elapses after the start of the process, a plurality of steps of etching at least one film layer of the film structure on the upper surface of the wafer 11 under different processing conditions are switched. It is carried out. Further, in this example, the processing conditions are changed from the processing in the previous process to the processing in the subsequent process between each of the two processes (processing steps) before and after the passage of time. A processing step having at least one transition step (transition step) is carried out.

When the processing of such a film structure is performed for a predetermined time and the end point of the processing is detected, the supply of high-frequency power from the high-frequency power source for forming the bias potential to the disk-shaped electrode inside the sample table 10 is stopped. Then, the etching process is stopped. After that, the adsorption due to the electrostatic force is eliminated and released. After that, the plurality of pins housed inside the sample table 10 are driven and move upward, and the wafer 11 placed on the upper ends of the plurality of pins is released and held above the upper surface of the sample table 10. In this state, the processed wafer 11 is delivered above the upper surface of the transfer device that has entered the processing chamber 4 again through the gate opened by the operation of the gate valve, and the transfer device moves out of the processing chamber 4 and the wafer 11 Is carried out and the gate is reclosed.

Next, a gas switching unit 100 having a gas switching mechanism provided in the plasma processing apparatus of this embodiment will be described.

The gas switching unit 100 of this embodiment is provided on an etching gas supply line 22 which is a first gas supply line connecting the gas supply unit 16 and the vacuum vessel 1 and on the etching gas supply line 22. It also includes a first valve 101 and a first valve 101. Further, it branches from the etching gas supply line 22 and connects between the turbo molecular pump 20 for exhaust of the processing chamber 4 and the dry pump 19 inlet for roughing arranged on the downstream side of the flow from the exhaust port. A first waste gas line 23 arranged so as to be connected to the exhaust line 21, and an etching gas supply line 22 and a first waste gas line 23 between the first valve 101 and the gas supply unit 16. It includes a first bypass line 104 connecting the spaces and a second valve 102 provided on the first bypass line.

Furthermore, the etching gas between the second waste gas line 24, which is branched from the etching gas supply line 22 and connected to the exhaust line 21, and the first valve 101 and the gas supply unit 16. A third bypass line 105 connecting the supply line 22 and the second waste gas line 24 and a third valve 103 provided on the third bypass gas line 105 are arranged. The first waste gas line 23 and the second waste gas line 24 are lines for discharging the processing gas flowing on the etching gas supply line 22 to the outside of the plasma processing apparatus through the dry pump 19.

Further, the gas switching unit 100 is supplied from the first transition step gas supply source 117 that supplies a rare gas such as argon or an inert gas into the processing chamber 4 in the transition step, and the first transition step gas supply source 117. On the second gas supply line 110 and the second gas supply line 110, through which the first transition step gas passes through the inside and connects between the first transition step gas supply source 117 and the etching gas supply line 22. A first transition step gas mass flow controller 116 is provided for adjusting the flow rate or speed of the first transition step gas. The second gas supply line 110 is connected to the etching gas supply line 22 between the first valve 101 and the chamber introduction gas line 25.

Further, in order to exhaust the fourth valve 111 provided on the second gas supply line 110 and the gas for the first transition step supplied from the second gas supply line 110 to the dry pump 19. A third bypass line 114 connecting between the second gas supply line 110 and the first waste gas line 23 and a fifth valve 112 provided on the third bypass line 114 are provided. There is. Further, in order to exhaust the first transition step gas supplied from the first transition step gas supply source 117 to the dry pump 19, there is a gap between the second gas supply line 110 and the second waste gas line 24. It includes a fourth bypass line 115 to be connected and a sixth valve 113 provided on the fourth bypass gas line 115.

Further, in the transition step, a second transition step gas supply source 127 for supplying a rare gas such as argon or an inert gas into the processing chamber 4, and a second transition step supplied from the second transition step gas supply source 127. A second gas supply line 120, which allows gas to pass through the inside and connects between the second transition step gas supply source 127 and the etching gas supply line 22, and a second gas supply line 120 arranged on the third gas supply line 120. It includes a second transition step gas mass flow controller 126 that adjusts the flow rate or speed of the transition step gas. The third gas supply line 120 is connected to the etching gas supply line 22 between the first valve 101 and the chamber introduction gas line 25.

Further, in order to exhaust the seventh valve 121 provided on the third gas supply line 120 and the gas for the second transition step supplied from the third gas supply line 120 to the dry pump 19. A fifth bypass line 124 connecting between the third gas supply line 120 and the first waste gas line 23 and an eighth valve 122 provided on the fifth bypass line 124 are provided. There is. Further, in order to exhaust the second transition step gas supplied from the second transition step gas supply source 127 to the dry pump 19, there is a gap between the third gas supply line 120 and the second waste gas line 24. It comprises a sixth bypass line 125 to be connected and a ninth valve 123 provided on the sixth bypass gas line 125.

Further, in the gas switching unit 100, a pressure gauge is arranged on each of the above gas lines, and a pressure gauge 106 for the chamber introduction gas line is arranged on the chamber introduction gas line 25 in the first waste gas line 23. The first waste gas line pressure gauge 131 is arranged, and the second waste gas line pressure gauge 141 is arranged in the second waste gas line 24.

Further, a variable conductance valve 132 is arranged on the first waste gas line 23, and a variable conductance valve 142 is arranged on the second waste gas line 24. For each of these variable conductance valves 132 and 142, the values detected by the first waste gas line pressure gauge 131 and the second waste gas line pressure gauge 141 were detected by the chamber introduction gas line pressure gauge 106. The flow rate and its speed are adjusted by increasing or decreasing the conductance such as the cross-sectional area of the flow path and the shape of the flow path in the pipe constituting the line according to the opening degree of the valve so as to be the same value as the value. The gas supplied to each of the first waste gas line 23 and the second waste gas line 24 is discharged to the outside of the plasma processing apparatus by the dry pump 19 through the exhaust line 21.

Next, the matching circuit 12 included in the plasma processing apparatus of this embodiment will be described with reference to FIG. FIG. 2 is a block diagram schematically showing an outline of a configuration of a matching circuit included in the embodiment shown in FIG.

As shown in this figure, the matching circuit 12 of this example is arranged on the feeding path connecting between the high frequency power supply 13 and the electrode made of a conductor built in the sample table 10, and the impedance is in the order of proximity to the high frequency power supply 13. The controller 26, the first variable element 27 for matching, and the second variable element 28 for matching are electrically connected to each other. Further, the matching circuit 12 is connected to the impedance external indicator 29 via a switch.

The switch cuts off and connects the electrical connection between each of the first matching variable element 27 and the second matching variable element 28 and the impedance external indicator 29. Further, the matching circuit 12 also includes a switch that cuts off and connects the electrical connection between the impedance controller 26 and the impedance external indicator 29.
By switching with these switches, the impedance controller 26 and the impedance external indicator 29 can be switched. When connected to the impedance controller 26, the impedance controller 26 adjusts the first matching variable element 27 and the second matching variable element 28 so that matching can be performed while monitoring the impedance deviation. When connected to the impedance external indicator 29, the impedance external indicator 29 adjusts the first matching variable element 27 and the second matching variable element 28 so as to have an arbitrary value. The switching by this switch can be switched when the high frequency power supply 13 is turned off.

Next, the etching process performed by this embodiment will be described with reference to FIGS. 3 and 4. FIG. 3 is a table showing some of the conditions in each of the plurality of steps of the etching process carried out by the embodiment shown in FIG. FIG. 4 is a graph showing the flow of operations in the process shown in FIG.

As described above, in this embodiment, between the two treatment steps before and after treating at least one membrane layer to be treated, the different conditions in these steps are changed from the previous one to the later one. It has a migration step. In particular, this transition step is divided into two, a transition step 1 and a transition step 2, and the former is followed by the latter.

In the transition step 1, among the processing conditions, the power for forming the electric field of the microwave supplied from the power source 8 for generating electromagnetic waves (microwave power) and the magnetic field supplied to the magnetic field generating coil 9 are formed. The current (magnetic field coil current) and the pressure inside the processing chamber 4 (processing chamber pressure) are maintained at their values under the conditions in the processing step A, which is the previous processing step. That is, in the transition step 1, the supply of the bias forming electric power (wafer bias electric power) supplied to the sample table 10 is stopped (turned off). Further, the gas flowing through the chamber introduction gas line 25 is switched to argon gas or an inert gas, and the flow rate thereof is the same as that of the processing gas in the processing step A.

In the transition step 2 to be performed next, among the processing conditions, the wafer bias power is maintained in the stopped (OFF) state, and the values of the microwave power, the magnetic field coil current, and the processing chamber pressure are each processed in the processing step. It is changed to that of the processing condition of B. Further, the flow rate of the argon gas or the inert gas flowing through the chamber introduction gas line 25 is changed so as to have the same value as the processing gas in the processing step B.

In this way, between the transition steps 1 and 2, the values of the processing conditions such as the microwave power, the magnetic field coil current, the processing chamber pressure, and the flow rate of the gas supplied to the processing chamber 4 are processed before and after the transition step. By changing the setting of the condition before the step to the one after the step, the time until the magnitude of the microwave power is changed and matched, the value of the magnetic field coil current and the value of the processing chamber pressure are changed and stabilized. Time is reduced and processing throughput is improved. Further, after the command signal for changing the above set value is received and the change is started, the change of the value of the actual condition is completed, or the value becomes a magnitude within a predetermined allowable range of fluctuation, so-called. The reproducibility of the profile of the transient response of each condition at the time of the transient response is improved, the difference in such transient response is reduced, and the processing yield is improved. Furthermore, regarding the matching of the wafer bias power, in the transition step 2 in which the wafer bias power is maintained in the OFF state, each of the first matching variable element 27 and the second matching variable element 28 is processed. By acquiring the matching value in B in advance and adjusting it to the matching value before the start of the processing step B, the influence of the transient response is suppressed.

Next, the gas flow inside the gas switching unit 100 in each step shown in FIG. 3 will be described with reference to FIGS. 5 to 8. In these figures, argon (Ar) is used as the inert gas, and the argon gas supplied from the first transition step gas mass flow controller 116 is the argon gas 1 (Ar1), and the second transition step gas mass flow controller. The argon gas supplied from 126 is shown as argon gas 2 (Ar2). Further, changes in the values of the gas flow rate passing through the first waste gas line 23 and the gas flow rate passing through the second waste gas line 24 in the etching process of the wafer 11 in which the steps shown in these figures are carried out are shown in FIG. 3. The flow of processing operation is shown in FIG.

FIG. 5 shows the gas flow inside the gas switching unit 100 in the processing step A. FIG. 5 is a diagram schematically showing a gas flow in the processing step A performed by the plasma processing apparatus according to the embodiment of FIG.

In this figure, at the start of the processing step A, the first valve 101 on the etching gas supply line 22 is opened based on a command signal from a control unit (not shown), and the gas supply unit 16 sets the condition A of the step. The etching gas as the processing gas to be used is adjusted by the mass flow controller arranged in the gas supply unit 16 so that the flow rate or the speed is that of the condition A, and the processing chamber 4 is passed through the chamber introduction gas line 25. Is supplied to. At this time, the pressure gauge 106 for the chamber introduction gas line detects the pressure in the chamber introduction gas line 25, and the pressure value is detected in the control unit to which the detection result is transmitted. Further, at the same time as the time when the first valve 101 is opened or at a time substantially close to this, the fifth valve 112 is opened in parallel, and the first transition step gas is opened. In the mass flow controller 116, the argon gas 1 (Ar1) having the same flow rate as the etching gas of the condition A is supplied to the first waste gas line 23 via the second gas supply line 110 and the third bypass line 114. Will be done.

Further, the ninth valve 123 is opened substantially at the same time as the opening of the first valve 101, and the condition B, which is the processing condition in the processing step B, in the mass flow controller 126 for the second transition step gas. Argon gas 2 (Ar2) adjusted to the same flow rate as the etching gas of the above is supplied to the second waste gas line 24 via the third gas supply line 120 and the fifth bypass line. The start of supply of the argon gas 1 to the first waste gas line 23 may include a time during the treatment step A until the flow rate or the speed of the argon gas 1 becomes equal to the condition A. Starting at a possible time, the flow rate or velocity of the argon gas 1 in the discarding first gas line 23 is maintained at that of condition A during the process step A. The start of supply of the argon gas 2 to the first waste gas line 24 is during the process step A or the transition step 1 until the flow rate or the speed of the argon gas 2 is equal to that of the condition B. The flow rate or speed of the argon gas 2 in the discarded second gas line 24 is maintained at the condition B during the period of the processing step A and the transition step 1.

That is, along with the flow of the argon gas 2 described above, the pressure in the first waste gas line 23 is detected by the pressure gauge 131 for the first waste gas line, and a signal indicating the result of this detection is transmitted to the control unit. The pressure is detected, and a command signal from the control unit is transmitted to the variable conductance valve 132 based on the detection result. From the operation of the variable conductance valve 132 based on the received command signal, the gas pressure in the first waste gas line 23 is set to the same value as that detected and detected by the pressure gauge 106 for the chamber introduction gas line. Be adjusted. Similarly, the pressure in the second waste gas line 24 is detected by the pressure gauge 132 for the second waste gas line, transmitted to the control unit to detect the pressure, and the variable conductance is based on the command signal from the control unit. By driving the valve 142, the pressure in the second waste gas line 24 is adjusted to be the same value as that of the pressure gauge 106 for the chamber introduction gas line.

In this state, the processing step A is executed, a signal indicating the end point detected by the end point determination device (not shown) is transmitted to the control unit to determine the end point, and the processing step A is stopped. Further, the transition step 1 is started based on the command signal from the control unit.

FIG. 6 shows the gas flow inside the gas switching unit 100 in the transition step 1. FIG. 6 is a diagram schematically showing a gas flow in the transition step 1 carried out by the plasma processing apparatus according to the embodiment of FIG.

At the start of the transition step 1, the first valve 101 on the etching gas supply line 22 is closed, the second valve 102 is opened, and the gas supply unit is set to the condition A based on the command from the control unit. The etching gas from 16 is supplied to the first waste gas line 23 via the first bypass line 104. Substantially in parallel with this, the fifth valve 112 is closed, the fourth valve 111 is opened, and the mass flow controller 116 for the first transition step gas allows the flow rate or velocity of the etching gas of condition A. Argon gas 1 adjusted to have the same value or substantially the same value as that of the gas is supplied to the processing chamber 4 through the second gas supply line 110 and the chamber introduction gas line 25 connected to the second gas supply line 110. Will be done.

Such a state is maintained during the transition step 1 and the argon gas 1 is supplied to the processing chamber 4 through the second gas supply line 110. Further, during the processing step 1, the operation of the variable conductance valve 142 is adjusted based on the command signal from the control unit to which the detection result of the pressure gauge 141 of the second waste gas line is transmitted, and the second waste gas line is discarded. The pressure of the gas line 24 is adjusted to be equal to or equal to that detected and detected by the pressure gauge 106 for the first gas supply line. When the control unit detects or determines that the transition step 2 has been started and a predetermined period has elapsed, the transition step 1 is stopped and the transition step 2 is started based on the command signal from the control unit. ..

FIG. 7 shows the gas flow inside the gas switching unit 100 in the transition step 2. FIG. 7 is a diagram schematically showing a gas flow in the transition step 2 carried out by the plasma processing apparatus according to the embodiment of FIG.

In this figure, at the start of the transition step 2, the fourth valve 111 is closed and the sixth valve 113 is opened based on the command signal from the control unit, and the mass flow controller 116 for the first transition step gas is opened. Argon gas 1 whose flow rate and velocity are adjusted so as to have the same values as the etching gas of condition A is supplied to the second waste gas line 24 via the second gas supply line 110 and the fourth bypass line 115. To. At this time, the operation of the variable conductance valve 142 is adjusted based on the command signal from the control unit, and the pressure in the second waste gas line 24 is the chamber detected from the detection result of the pressure gauge 106 for the chamber introduction gas line. The value is adjusted to be the same as or substantially the same as that of the introduced gas line 25.

Further, at the same time as above or substantially in parallel with the above, the ninth valve 123 is closed and the seventh valve 121 is opened, and the process in the process step B is performed by the mass flow controller 126 for the second transition step gas. The argon gas 2 (Ar2) whose flow rate and velocity were adjusted so as to be equal to or substantially the same as the flow rate and velocity of the etching gas under the condition B was connected to the second gas supply line 120. It is supplied to the processing chamber 4 via the chamber introduction gas line 25. At this time, the pressure in the second waste gas line 24 is changed from a signal indicating the detection result from the pressure gauge 141 for the second waste gas line to a command signal from the control unit according to the result detected by the control unit. Based on this, the operation of the variable conductance valve 142 is adjusted to be equal to or equivalent to that in the chamber introduction gas line 25.

Further, during the start or end of the transition step 2, the etching gas supplied from the gas supply unit 16 based on the command from the control unit has its flow rate or its speed and other values determined from condition A to condition B. It is adjusted and changed to be the one. At this time, the etching gas from the gas supply unit 16 is supplied to the first waste gas line 23 as in the transition step 1. Further, as shown in FIG. 4, in the transition step 1, the processing chamber pressure and the microwave power, which have been set to the values of the conditions of the processing step A, are processed during the period between the start time and the end time of the transition step 2. It is changed to that of step B.

FIG. 8 shows the gas flow inside the gas switching unit 100 in the processing step B. FIG. 8 is a diagram schematically showing a gas flow in the processing step B carried out by the plasma processing apparatus according to the embodiment of FIG. When the control unit detects or determines that the transition step 2 has been started and a predetermined time has elapsed, a command signal from the control unit is transmitted to each unit of the plasma processing apparatus, the transition step 2 is stopped, and the processing step is stopped. B is started.

In this figure, at the start of the processing step B, the second valve 102 on the first gas supply line 22 is closed and the first valve 101 is opened based on the command signal from the control unit to supply gas. Etching gas adjusted from the unit 16 to a value equivalent to the flow rate or velocity value of the condition B is supplied to the processing chamber 4 via the chamber introduction gas line 25. Further, at the same time or substantially in parallel with this, the seventh valve 121 is closed and the eighth valve 122 is opened, and the mass flow controller 126 for the second transition step gas next to the processing step B. The argon gas 2 adjusted to have the same or substantially the same flow rate and speed as the flow rate and speed of the etching gas used in the condition C, which is the treatment condition of the treatment step C, is the third gas supply line 120. It is supplied to the first waste gas line 23 via the fourth bypass line 124.

Further, during the treatment step B, the pressure in the second waste gas line 24 to be supplied with the flow rate or speed adjusted so that the argon gas 1 is equal to or equal to that of the treatment step B is the second pressure. The operation of the variable conductance valve 142 is adjusted based on the command signal from the control unit according to the value detected using the detection result of the waste gas line pressure gauge 141, and the chamber introduction gas line pressure gauge 106 and Adjusted to the same value. Further, other processing conditions such as microwave power and wafer bias power are adjusted based on a command signal from the control unit so as to be those of condition B, plasma is formed in the processing chamber 4, and processing step B Etching process is carried out from the detection result of the end point determination device until the arrival at the end point of the process is detected by the control unit.

If there is a treatment step C and a transition step to the treatment step B after the treatment step B, the transition step 1 and the subsequent transition step 1 in which the conditions are adjusted to be equivalent to those of the previous treatment step and the noble gas is supplied are the same as above. The treatment step is carried out as long as necessary, with the transition step 2 in which the noble gas is introduced and the conditions are adjusted to be equivalent to those of the treatment step.

In the processing of the wafer 11 in which a plurality of processing steps with different processing conditions are carried out by the plasma processing apparatus having the above configuration, the time until the processing conditions are changed and stabilized is reduced, and the processing is performed. Throughput is improved. Further, a so-called transient response in which the change of the value of the actual condition is completed after the command signal of the above change is received and the change is started, or the value becomes a magnitude within a predetermined allowable range of fluctuation. The reproducibility of the profile of the transient response of each condition in time is improved, the difference in such transient response is reduced, and the processing yield is improved.

In the above embodiment, the pressure in the exhaust line 21 is the pressure inside the first and second waste gas lines 23 and 24 to which one end is connected to the exhaust line 21, that is, in the chamber introduction gas line 25. It is significantly smaller than the pressure, and the flow rate and speed of the exhaust gas can maintain the pressure in the processing chamber 4 under the conditions A and B. Therefore, even if the gas from the first and second waste gas lines 23 and 24 flows in at a predetermined flow rate and speed, the pressure, flow rate, and speed inside these gas lines may fluctuate greatly. It is suppressed.

The present invention is not limited to the above-described examples, and includes various modifications. For example, in the transition steps 1 and 2 described with reference to FIGS. 6 and 7, plasma is formed in the processing chamber 4 using argon gases 1 and 2, the wafer bias power is stopped, and the processing of the wafer 11 proceeds. Is suppressed. On the other hand, in the transition steps 1 and 2, the plasma may be extinguished and the processing may be stopped, and the microwave power may not be introduced into the processing chamber 4 through the waveguide 6 by changing only the set value. good.

Further, in the above embodiment, the etching gas supply line 22, the second gas supply line 110 and the second gas supply line 120, the chamber gas introduction line 25, the first waste gas line 23 and the second waste gas Two bypass lines and three valves are arranged in each of the lines 24 and the chamber, and each line is opened and airtightly closed in response to a command signal from the control unit. A configuration is provided in which the communication between the gas introduction line 25 and each supply line and the communication between each supply line and each waste gas line can be switched. A smaller number of these three valves, such as a four-way valve, may be used. In this case, at least one of the etching gas supply line 22, the second gas supply line 110, and the second gas supply line 120 is provided with each supply line and the chamber gas supply line 25 in addition to such a valve. A valve may be provided between the three supply lines to open the gas flow and close the airtightness.

Further, as the etching gas used in the treatment step A and the treatment step B, those having different types and compositions of substances used may be used, and even if the same type and composition but different flow rates or velocities are used, the types may be different. , Only one of the compositions may be different. Further, the type of rare gas used may be different in the transition steps 1 and 2. The above-described embodiment has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to the one including all the described configurations.

1 ... Vacuum container 2 ... Shower plate 3 ... Dielectric window 4 ... Processing chamber 5 ... Vacuum exhaust port 6 ... GmbH tube 7 ... Cavity resonator 8 ... Power supply for electromagnetic wave generation 9 ... Magnetic field generation coil 10 ... Sample stand 11 ... Wafer 12 ... Matching circuit 13 ... High frequency power supply 14 ... Filter 15 ... DC power supply for electrostatic adsorption 16 ... Gas supply unit 17 ... Pressure gauge 18 ... Variable conductance valve 19 ... Dry pump 20 ... Turbo molecular pump 21 ... Exhaust line 22 ... Etching gas Supply line 23 ... 1st waste gas line 24 ... 2nd waste gas line 25 ... Chamber introduction gas line 26 ... Impedance controller 27 ... 1st matching variable element 28 ... 2nd matching variable element 29 ... External impedance Indicator 100 ... Gas switching unit 101 ... First valve 102 ... Second valve 103 ... Third valve 104 ... First bypass line 105 ... Second bypass line 106 ... Chamber introduction gas line pressure gauge 110 ... 2nd gas supply line 111 ... 4th valve 112 ... 5th valve 113 ... 6th valve 114 ... 3rd bypass line 115 ... 4th bypass line 116 ... 1st transition step Gas mass flow controller 120 ... 3rd gas supply line 121 ... 7th valve 122 ... 8th valve 123 ... 9th valve 124 ... 5th bypass line
125 ... 6th bypass line 126 ... 2nd transition step Gas mass flow controller 131 ... 1st waste gas line pressure gauge 132 ... Variable conductance valve 141 ... 2nd waste gas line pressure gauge 142 ... Variable conductance valve

Claims (5)

A processing chamber arranged inside the vacuum vessel, a gas supply unit that supplies a predetermined flow rate of processing gas into the processing chamber, and a sample table arranged in the processing chamber and on which a wafer to be processed is placed. A plasma processing apparatus that processes the wafer in a step including a plurality of processing steps for forming plasma in a processing chamber using the processing gas supplied under different conditions.
The step is a transition step in which a noble gas is supplied into the treatment chamber between the two treatment steps before and after the rare gas, and the pressure of the rare gas is applied to the treatment gas used in the previous treatment step. The processing gas used in the subsequent processing step for the first transition step, which is adjusted and supplied so as to be equal to the conditions, and the pressure and flow rate of the noble gas after the first transition step. comprising a transition step and a second transition step is adjusted to be equal to the conditions in the supply,
The gas supply unit includes a gas introduction line connected to the vacuum vessel, a first gas supply line for supplying the processing gas used in the plurality of processing steps communicated with the gas introduction line, and the first gas supply line. An exhaust pump connected to each of the second and third gas supply lines and the first, second and third gas supply lines to which the rare gas used in each of the first and second transition steps is supplied. Communication between the first and second waste gas lines, the first, second, and third gas supply lines, the gas introduction line, and each of the first and second waste gas lines. A plasma processing apparatus including at least one valve that opens and closes the gas, and a control unit that switches the valve according to the two processing steps of the step and the first and second transition steps between them.
The plasma processing apparatus according to claim 1.
The control unit supplies the rare gas to the first waste gas line during the previous processing step under the conditions used in the first transition step, and the rare gas during the first transition step. A plasma processing apparatus that adjusts the operation of the valve so that the gas is supplied to the second waste gas line under the conditions used in the second transition step.
The plasma processing apparatus according to claim 1 or 2.
A plasma processing apparatus provided above each of the first and second waste gas lines and provided with first and second adjusting valves for adjusting the pressure of gas flowing through the inside.
A predetermined flow rate of processing gas is supplied to the processing chamber arranged inside the vacuum vessel through the gas supply unit, and the wafers to be processed placed on the upper surface of the sample table arranged in the processing chamber are different from each other. A plasma processing method for processing a wafer by a step including a plurality of processing steps of forming and processing plasma in a processing chamber using the processing gas supplied under the conditions.
The step is a transition step in which a noble gas is supplied into the treatment chamber between the two treatment steps before and after the rare gas, and the pressure of the rare gas is applied to the treatment gas used in the previous treatment step. The processing gas used in the subsequent processing step for the first transition step, which is adjusted and supplied so as to be equal to the conditions, and the pressure and flow rate of the noble gas after the first transition step. A transition step including a second transition step that is adjusted and supplied to be equal to the conditions of
The gas supply unit includes a gas introduction line connected to the vacuum vessel, a first gas supply line for supplying the processing gas used in the plurality of processing steps communicated with the gas introduction line, and the first gas supply line. An exhaust pump connected to each of the second and third gas supply lines and the first, second and third gas supply lines to which the rare gas used in each of the first and second transition steps is supplied. Communication between the first and second waste gas lines, the first, second, and third gas supply lines, the gas introduction line, and each of the first and second waste gas lines. Equipped with at least one valve that opens and closes
A plasma processing method for processing the wafer by switching the valve according to the two processing steps of the step and the first and second transition steps between them.
The plasma processing method according to claim 4.
During the previous treatment step, the noble gas is supplied to the first waste gas line under the conditions used in the first transition step, and during the first transition step, the noble gas is the second. A plasma treatment method supplied to the second waste gas line under the conditions used in the transition step.

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